Vitreous Detachment

Posterior vitreous detachment (PVD) is a common condition usually caused by aging. The vitreous, which lies against the retina, is the jelly-like substance that fills the center of the eye. Made mostly of water, the vitreous fluid gives the eye its shape. As we get older, the composition of the vitreous changes, becoming less firm. This change sometimes causes the vitreous to pull on the retina. If the force of the pulling becomes strong enough, the vitreous may actually separate from the retina. This common condition is called a posterior vitreous detachment, as it normally occurs at the back (posterior) of the eye.

Why the Vitreous Detaches:

In children, the vitreous has a consistency similar to that of an egg white. As we age, the center of the vitreous becomes more watery, causing the outer edges to shrink and peel away from the retina. If this shrinking process occurs suddenly, it is called a posterior vitreous detachment. PVD is usually not a big concern or threat to vision, but as complications can occur, an eye doctor should always evaluate the condition.

Many retinal detachments are associated with posterior vitreous detachment (PVD), a common condition in which the vitreous gel shrinks and separates from the retina.

Posterior vitreous detachment usually results from normal, age-related changes in the vitreous gel (although it can also result from eye injury or inflammation from surgery or disease). PVD affects more than 25% of people between ages 60 and 69 and more than 60% of people age 70 and older.

As a person ages, the vitreous gel in the middle of the eye begins to change. The gel's normal structure breaks down in a process called syneresis. Parts of the gel shrink and lose fluid. The fluid collects in pockets in the middle of the eye, and thick strands of the gel form and drift through the eye. These strands appear as dark floaters.

Sometimes these changes cause the vitreous gel to shrink suddenly and separate from the retina. This is called posterior vitreous detachment.

Posterior vitreous detachment usually does not cause any problems, but it can sometimes cause tears in the retina. At points where the vitreous gel is strongly attached to the retina, the vitreous can pull so hard on the retina that it tears the retina. The tear then allows fluid to collect under the retina and may lead to a retinal detachment.

The main symptoms of PVD are dark floaters and flashes of light. It is important to pay attention to these symptoms because they could be warning signs of a retinal tear or detachment.

The majority of the muscles in your face are controlled by a single nerve, known as the facial nerve.

The facial nerve passes through a narrow gap of bone on its way from your brain to your face. Bell's palsy is thought to occur because a virus, usually the herpes virus, causes the nerve to become inflamed. If the nerve is inflamed, it will press against the cheekbone.

If the facial nerve is compressed, it is likely to become damaged, interfering with the signals that your brain is sending to the muscles in your face. The interference results in the weakness, or paralysis, that is characteristic of cases of Bell's palsy.

 

If you experience a sudden onset of flashes and floaters, you may be experiencing a posterior vitreous detachment and need to be examined by an eye doctor. The doctor will most likely dilate your eyes and carefully check for possible tears in the retina. If retinal tears are discovered, your doctor will need to seal them to prevent a retinal detachment. Sealing retinal tears is usually accomplished by laser or freezing treatment.

PVD sometimes happens with no symptoms. For some people, however, the experience can be quite alarming. Some people may notice flashes of light or floaters.

  • Flashes: Flashes of light may occur as the vitrous pulls on the retina because the brain interprets all signals from the retina as light. The flashes usually last for a couple of weeks and then go away, causing no threat to vision.
  • Floaters: Small particles of pigment may break off of the retina, appearing as spots or strings in the vision. The brain will usually adapt to large or stubborn floaters over time, making them less annoying.

If the retina is not torn by the vitreous separation, no treatment is required. However, when the retina has become torn, surgery may be required. The goal of treating a retinal tear is to form a scar to seal the area around it. The type of sealing "glue" that can be obtained with cryosurgery (freezing) or laser surgery. Both treatments are outpatient and achieve the same result – sealing the retina around the tear so that retinal detachment will not occur. Laser treatment is performed in the upright position while cryotherapy is performed in the reclining position. The eye is anesthetized using an injection behind the eye or an anesthetic eye drop.

The choice between the use of freezing or laser depends on the size and location of the tear, haziness from bleeding within the eye, cataract change and other factors. Your surgeon will discuss the appropriate form of treatment with you.